Returning element of pointer array member variable

Question

I'm new to pointers and having a hard time. I'm doin a predator-prey simulator and have a City class that has an array of Being objects, which are eventually to be cast as either Humans or Zombies. City class has an array:

class City
{
protected:
    Being *grid[GRID_HEIGHT][GRID_WIDTH];//holds beings

I initialize the elements to null to start with just to keep it simple.

City::City()
{
    for (int i = 0; i < GRID_HEIGHT; ++i) {
        for (int j = 0; j < GRID_WIDTH; ++j) {
            this->grid[i][j] = NULL;
        }
    }
}

I also have a method that should return a single Being from the array. THIS is where I am getting errors: "identifier 'grid' is undefined" or if I use the "this" keyword it says that's only allowed in a nonstatic member function.

Being City::*getBeing(int x, int y)
{
    return grid[x][y];
}

so I can access it from the main method and just print a placeholder grid:

City myCity;

int main(){
        if (myCity.getBeing(i,j) == null)
        {
            cout << "O";
        }
}

How can I fix this? Is there a rule of thumb for understanding pointers better?

simpel01 · Accepted Answer · 2015-12-02 20:25:06Z

3

Definition of the getBeing function should be:

Being *City::getBeing(int x, int y) { ... }

answered Dec 2, 2015 at 20:25

simpel01

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2 Comments

Angela Kay Over a year ago

It was that easy. Also for future reference, I also changed the NULL initializer to 0 as I had an error in the main class of "identifier null is undefined". Thanks!

simpel01 Over a year ago

it should be NULL, not null. If you are using C++11 I strongly suggest you use nullptr instead!

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